厦门大学海洋与地球学院

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Tracking Typhoon Eye over Ocean Surface Using Multiple Satellite Sensors

2014/10/28 2695

1900-01-01 11月5日上午10:10-11:30

刘安国教授

周隆泉楼A3-206

Abstract:
In this study, typhoon eyes have been delineated using wavelet analysis from synthetic aperture radar (SAR) and infrared (IR) images to detect the “eyes” on the sea surface and at the cloud top, respectively. RADARSAT and ENVISAT SAR imagery and multi-functional transport satellite (MTSAT) and Feng Yun Chinese meteorological satellite (FY)-2 IR and optical/visible (VIS) imagery were used to examine the typhoons in the western North Pacific from 2005 to 2011. Fifteen cases of various typhoons in different years, locations, and conditions were used to compare the typhoon eyes by SAR (near the ocean surface) with IR (at the cloud-top level) images. Furthermore, the best track data getting from the Joint Typhoon Warning Center (JTWC), Chinese Meteorological Administration (CMA) and Japan Meteorological Agency (JMA) are checked for the calibration and validation along with the Moderate Resolution Imaging Spectroradiometer (MODIS) image. Consequently, the large horizontal distance between typhoon eyes on the ocean surface and on the cloud top implies that the vertical wind shear profile is considerably more complex than generally expected, which has been but should not be ignored in typhoon forecasts and numerical simulations. The upright tilt may also be caused by the ocean's feedback or the effect of island obstruction. Then, based on nine typhoon cases, the horizontal shifts and vertical tilt angles from the cloud–top typhoon eye locations by IR sensors onboard FY-2 and MTSAT to that at sea surface by SAR are further estimated. This shift difference between different sensors brings up an issue on project distortion and navigation system errors for FY-2 and MTSAT satellites. This study demonstrates that SAR can be a useful tool for typhoon monitoring over the ocean surface. Further study on typhoon wind speeds by tracking rainbands from various sequential sensors, including coastal Doppler radar, will also be discussed.

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